Environ. Sci. Technol. 2007, 41, 2861-2867
Development of a House Dust Standard Reference Material for the Determination of Organic Contaminants D I A N N E L . P O S T E R , * ,† JOHN R. KUCKLICK,‡ MICHELE M. SCHANTZ,† STACY S. VANDER POL,‡ STEFAN D. LEIGH,§ AND STEPHEN A. WISE† Analytical Chemistry Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8392, Hollings Marine Laboratory, Analytical Chemistry Division, National Institute of Standards and Technology, Charleston, South Carolina 29412, and Statistical Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8980
National-level health survey studies, such as the National Human Exposure Assessment Survey field program, have targeted the determination of organic contaminants in house dust in an effort to characterize human exposure in the domestic environment. As the effort to further understand human health effects in relation to organic contaminants associated with indoor dust accelerates, the need for an indoor dust Standard Reference Material (SRM) that is characterized for organic contaminants has become critical. To meet this need, a new organic contaminant house dust SRM has been developed. SRM 2585 Organic Contaminants in House Dust is intended for use in evaluating analytical methods for the determination of selected polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyl (PCB) congeners, chlorinated pesticides, and polybrominated diphenyl ether (PBDE) congeners in house dust and similar matrices. The material may also be useful for evaluation and comparison of methods or instruments used for sampling in the indoor environment. Moreover, because of the material’s extensive characterization (140 organic contaminant concentrations), the material may be useful in toxicity studies related to indoor air (in vitro or in vivo). The determination of the concentrations of PAHs (including alkyl-PAHs and PAHs with molecular mass 300 and 302), PCBs, and chlorinated pesticides is reported here, and these results are compared to values reported in the literature for house dust.
Introduction About 25 years ago, it became clear that organic compounds within a building accumulated in the particulate matter circulating within and throughout the same building (1). However, the reporting of organic contaminants in indoor * Corresponding author phone: (301)975-4166; fax: (301)977-0685; e-mail:
[email protected]. † Analytical Chemistry Division. ‡ Hollings Marine Laboratory. § Statistical Engineering Division. 10.1021/es061966z CCC: $37.00 Published on Web 03/21/2007
2007 American Chemical Society
air particulate matter has been sparse through the late 1990s (2, 3). Since then, it has become clear that organic contaminants are prevalent in house dust (4-13), and mutagenic hazards have been identified with this matrix (14). Moreover, national-level health survey studies, such as the U.S. Environmental Protection Agency’s (U.S. EPA) National Human Exposure Assessment Survey (NHEXAS) field program (15), have targeted the determination of organic contaminants in house dust in an effort to characterize human exposure in the domestic environment, that is, indoor dust is one indicator of interior exposure (16-18). Inhalation, dermal adsorption, and incidental dietary and nondietary ingestion of house dust are now recognized as important exposure and uptake (i.e., accumulation) pathways for organic contaminants (19, 20). The Agency for Toxic Substances and Disease Registry collected house dust in conjunction with soil and blood samples to assess polychlorinated biphenyl (PCB) exposure in members of a residential community living near a plant that formerly manufactured PCBs (21), and organic contaminants were determined in house dust as part of a German environmental survey (22). Polycyclic aromatic hydrocarbon (PAH) concentrations and organotins in house dust from apartments in Berlin are under study (23, 24). The National Children’s Study, a longitudinal epidemiologic study of children’s health, includes the collection and analysis of indoor dust (25, 26). The Minnesota Children’s Pesticide Exposure Study, a unique probability-based sampling effort to study multipathway and multipesticide exposures in children (16), included the collection of dust for the determination of pesticides and PAHs (27). Recently, as part of a population-based control study conducted in selected areas in the United States covered by the Surveillance, Epidemiology, and End Results Program of the National Cancer Institute, Colt et al. (28) examined non-Hodgkin lymphoma risk and exposure to organochlorine compounds using concentrations in carpet dust as an exposure indicator. As the effort to further understand human health effects in relation to organic contaminants associated with indoor dust accelerates, the need for an indoor dust Standard Reference Material (SRM) that is characterized for a wide range of organic contaminants has become critical. Efforts to establish performance evaluations and to determine what dust samples represent are necessary for developing approaches to use indoor dust in research, regulation, or forensic investigations (18). Historically, the National Institute of Standards and Technology (NIST) has had a major qualityassurance role in the federal effort to reduce and monitor lead levels in children through the production of SRMs that are characterized for lead content. In cooperation with the U.S. EPA, the U.S. Department of Housing and Urban Development, and the U.S. Geological Survey, NIST produced a range of SRMs for the determination of lead in indoor dust, paint, and soil (29). Actual house dust was collected and used to prepare two indoor dust SRMs: SRM 2583 Trace Elements in Indoor Dust, Nominal 90 mg kg-1 Lead (released in 1996) and SRM 2584 Trace Elements in Indoor Dust, Nominal 1% Lead (released in 1999). SRM 2583 was prepared with the intent to provide a background-level material for the determination of lead in indoor dust. SRM 2584 was prepared from dust collected from sites associated with lead poisoning cases. Additional elements were certified in both SRMs (mercury, cadmium, chromium, and arsenic). These materials were not examined for organic contaminants until recently (30), although Lewis et al. reported 10 PAH concentrations in SRM 2583 (8). Moreover, no indoor dust material was available that was solely characterized for VOL. 41, NO. 8, 2007 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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TABLE 1. Certified Concentrations (Mass Fractions in µg kg-1 Dry Mass)a for PAHs in SRM 2585 PAHs
valueb
naphthalene dibenzothiophene phenanthrene anthracene 4H-cyclopenta[def]phenathrene 3-methylphenanthrene 2-methylphenanthrene 9-methylphenanthrene 1-methylphenanthrene fluoranthene pyrene benzo[ghi]fluoranthene benzo[c]phenanthrene benz[a]anthracene chrysene triphenylene benzo[b]fluoranthene benzo[j]fluoranthene benzo[k]fluoranthene benzo[a]fluoranthene benzo[e]pyrene benzo[a]pyrene perylene benzo[ghi]perylene indeno[1,2,3-cd]pyrene dibenz[a,j]anthracene dibenz[a,c]anthracene dibenz[a,h]anthracene benzo[b]chrysene picene coronene dibenzo[b,k]fluoranthenec dibenzo[a,e]pyrenec
266 109 1920 96.0 117 293 352 205 197 4380 3290 317 288 1160 2260 589 2700 1320 1330 74.5 2160 1140 387 2280 2080 267 183 301 182 413 603 596 477
( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( (
uncertaintyb
PAH
valueb
8 8 20 5.2 10 36 40 16 29 100 30 11 10 54 60 17 90 110 70 8.1 80 10 23 40 100 9 25 50 6 15 38 22 67
1-methylnaphthalene 2-methylnaphthalene biphenyl retene 1,7-dimethylphenanthrene 1-methylfluroanthene 3-methylfluoranthene 8-methylfluoranthene 4-methylpyrene 2-methylpyrene 1-methylpyrene 3-methylchrysene 2-methylchrysene 6-methylchrysene 4-methyl- and 1-methylchrysene 9-methyl- and 3methylbenz[a]anthracene 6-methyl- and 1methylbenz[a]anthracene anthanthrene dibenzo[b,e]fluoranthene (peak # 1)c naphtho[1,2-b]fluoranthene (peak # 3) naphtho[1,2-k]- and naphtho[2,3-j]fluoranthene (peak # 4 + 5) naphtho[2,3-b]fluoranthene (peak # 7) naphtho[2,3-k]fluoranthene (peak # 14) dibenzo[a,k]fluoranthene (peak # 9) dibenzo[j,l]fluoranthene (peak # 10) dibenzo[a,l]pyrene (peak # 12) naphtho[2,3-k]fluoranthene and naphtho[1,2-a]pyrene (peak # 14 + 15) naphtho[2,3-e]pyrene (peak # 17) naphtho[2,1-a]pyrene (peak # 20) dibenzo[e,l]pyrene (peak # 21) benzo[b]perylene (peak # 23) dibenzo[a,i]pyrene (peak # 24) dibenzo[a,h]pyrene (peak # 25)
150 227 88 588 219 94 235 132 235 345 209 146 181 88 94.8 92.3
( ( ( ( ( ( ( ( ( ( ( ( ( ( ( (
37 20 21 34 19 11 67 7 27 10 69 18 4 14 4.8 2.5
155
(
5
91 59.6 312 382
( ( ( (
27 7.5 10 18
93 24.7 14.3 260 42.3 44.3
( ( ( ( ( (
30 1.2 3.4 26 3.1 1.9
145 379 208 103 105 20.9
( ( ( ( ( (
29 47 14 24 11 0.7
a Material as received contains approximately 2.1% moisture. b Values are the means of results from multiple analytical methods (SI Table 2); uncertainties are expanded uncertainties about the means; see SI Table 2 for a description of the approach used to calculate each value and uncertainty (33). c PAHs with molecular mass 302, additional compounds in Table 2. In SI Figure 3, dibenzo[b,k]fluoranthene is peak number 8 and dibenzo[a,e]pyrene is peak number 18.
organic contaminants. To address this gap, a new indoor dust reference material has recently been prepared and characterized for organic contaminants: SRM 2585 Organic Contaminants in House Dust. To our knowledge, this is the first and only indoor dust certified reference material characterized for organic contaminants. The development of SRM 2585 and the characterization of PAHs, PCB congeners, and chlorinated pesticides in the material are described in this paper. Contaminant concentrations are presented and compared to those determined in particle-related SRMs, such as SRM 1649a Urban Dust (31, 32), and to values reported in the literature for house dust. SRM 2585 is the most extensively characterized SRM for organic contaminants (140 concentrations (33) for PAHs, PCB congeners, chlorinated pesticides, and polybrominated diphenyl ether congeners (PBDEs (30, 33)), making this the most useful reference material available for surveys related to indoor air quality. The use of SRM 2585 will provide one critically lacking mechanism for researchers to evaluate the quality and comparability of their performance in measuring selected organic contaminants in indoor dust. SRM 2585 will also be useful for evaluation and comparison of methods or instruments used for sampling in the indoor environment. In addition, because of the material’s extensive characterization, SRM 2585 is a prime candidate for use in toxicity studies related to indoor air. No indoor dust standard material is available for use in toxicity testing, limiting the comparability of data and conclusions drawn from in vitro and in vivo 2862
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TABLE 2. Reference Concentrations (Mass Fractions in µg kg-1 Dry Mass)a for PAHs in SRM 2585
ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 41, NO. 8, 2007
uncertaintyb
a Material as received contains ≈2.1% moisture. b Values are means of results from one to three analytical methods (SI Table 2), and uncertainties are expanded uncertainties about the means; see SI Table 2 for a description of the approach used to calculate each value and uncertainty (33). c See SI Figure 3 for GC chromatograms of these PAHs (molecular mass 302) in SRM 2585 and in an air particulate SRM and a coal tar SRM where peaks are identified by number listed.
indoor dust studies. NIST diesel particulate-related SRMs have been widely used in genotoxicity and mutagenicity studies (reviewed in ref 34) as well as in air particulate SRMs and in a coal tar SRM (SI Table 1).
Methods The collection of dust for the preparation of SRM2585 and the determination of the material’s moisture content and homogeneity are described in Supporting Information (SI). Organic Contaminant Determination. The approach used for the value assignment of the PAHs (32, 35, 36) and PCBs and chlorinated pesticides (31, 35-37) in SRM 2585 was similar to that reported for the recent certification of environmental SRMs and consisted of combining results from analyses using combinations of different extraction techniques and solvents, cleanup/isolation procedures, and chromatographic separation and detection techniques. We have recently reviewed the history and development of this state-of-the-art, multilevel analytical approach for the determination of organic contaminants in environmental natural-matrix SRMs (38). For the determination of PAHs in SRM 2585, gas chromatography (GC) analysis was coupled with mass spectrometry (GC/MS) and the use of three GC stationary phases with different selectivity: a 50% (mole
TABLE 3. Certified and Reference Concentrations (Mass Fractions in µg kg-1 Dry Mass)a,b for PCBs and Pesticides in SRM 2585 valueb PCB 18 PCB 28 PCB 31 PCB 44 PCB 49 PCB 52 PCB 56 PCB 63 PCB 66 PCB 70 PCB 74 PCB 87 PCB 92 PCB 95 PCB 99 PCB 101 PCB 105 PCB 107 PCB 110 PCB 118 PCB 121 PCB 128 PCB 138 PCB 146 PCB 149 PCB 151 PCB 153 + 132 PCB 158
12.8 13.4 14.0 18.1 (16.4 21.8 4.42 (6.69 (8.5 13.1 5.22 16.6 5.48 22.7 11.6 29.8 13.2 4.14 28.1 26.3 (18.7 (8.1 27.6 4.89 24.4 6.92 40.2 4.50
uncertaintyb ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( (
1.0 0.5 0.5 1.9 3.3) 1.9 0.28 0.26) 1.9) 1.2 0.51 0.8 0.72 2.6 0.4 2.3 1.4 0.47 3.7 1.7 0.4) 1.6) 2.1 0.38 1.9 0.64 1.8 0.43
valueb PCB 163 PCB 170 PCB 174 PCB 177 PCB 178 PCB 180 PCB 183 PCB 185 PCB 187 PCB 193 PCB 194 PCB 199 PCB 206 PCB 209 4,4′-DDE 4,4′-DDD 2,4′-DDT 4,4′-DDT cis-chlordane trans-chlordane cis-nonachlor trans-nonachlor heptachlor heptachlor epoxide dieldrin gamma-HCH mirex pentachlorobenzene
7.2 8.8 8.83 (5.50 (2.17 18.4 5.27 (5.32 11.3 (1.23 (4.47 (5.81 3.81 (2.14 261 27.3 44.5 111 (174 (277 (28.0 (130 (166 (11.3 (88 (4.06 (6.89 (20.9
uncertaintyb ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( (
1.2 1.0 0.47 0.44) 0.16) 3.2 0.39 0.39) 1.4 0.070) 0.76) 0.38) 0.13 0.11) 2 0.8 3.9 23 45) 96) 0.6) 38) 34) 0.6 21) 0.55) 0.25) 1.6)
a Material as received contains approximately 2.1% moisture. b Values in parentheses are listed as reference values, values are the means of results from one to four analytical methods and uncertainties are expanded uncertainties; see SI Table 3 for a description of the approach used to calculate each value and uncertainty as well as for as a description of PCB congener numbers (33).
fraction) phenyl-substituted methylpolysiloxane phase, a relatively nonpolar proprietary phase, and a liquid-crystalline phase (SI Figure 1). For the determination of PCBs and chlorinated pesticides in SRM 2585, the same multiplemethod approach was used, although GC analyses consisted of GC/MS and GC with electron capture detection (GC-ECD) on three columns with different selectivity for the separation of PCBs and chlorinated pesticides (SI Figure 2). Seven sets of GC/MS results were obtained for PAHs (SI Table 2). Four sets of results were obtained for PCBs and chlorinated pesticides (SI Table 3). Each method is described in SI.
Results and Discussion PAH Concentrations. The concentrations of PAHs determined in SRM 2585 using the different analytical methods described in SI are summarized in SI Table 2. The use of three different GC columns permits the determination of PAHs that may coelute on one column and reduces the possibility of biases because of coelution of interferences. We recently reviewed PAH separations via GC and presented chromatograms from the GC/MS analysis of SRM 2585 on each of the three columns listed in SI Table 2 for selected isomers (39). Separations of chrysene and triphenylene, which coelute on a 50% phenyl methylpolysiloxane column, are demonstrated on a nonpolar column and a liquid-crystalline column. Additional PAHs, such as benzo[b]- and benzo[j]fluoranthene, and dibenz[a,c]- and dibenz[a,h]anthracene, also separate on this liquid-crystalline phase column, although benzo[a]- and benzo[j]fluoranthene coelute (see Figure 5 in ref 39). We have reviewed the use of liquidcrystalline columns for the determination of PAHs (40), including six-ring C24H14 PAHs (39, 41). Interestingly, there are no reports of six-ring C24H14 PAHs in house dust despite the fact that these compounds are widespread in the environment (42-48). Many are genotoxic (49-52). The U.S. EPA is assessing this group of PAHs in its
programs related to health evaluations (53). These compounds are prevalent in SRM 2585. The C24H14 isomer signature is not only complex but is also similar to that found in ambient air particulate matter and coal tar (SI Figure 3). Concentration values have been assigned for 19 C24H14 PAHs in SRM 2585 on the basis of a combination of the concentrations obtained from the various analytical methods (SI Table 2). To date, six environmental natural-matrix SRMs have been characterized for these compounds: two sediments, coal tar, house dust, and diesel and air particulate matter (38). PCB and Chlorinated Pesticide Concentrations. Up to four methods of analysis (SI Figure 2) were used for the determination of the concentrations of 42 PCB congeners and 14 pesticides in SRM 2585 (SI Table 3). Aspects of the SRM 2585 chlorinated contaminant analytical scheme include the use of carbon-13 labeled analytes as internal standards and the use of GC/MS with negative chemical ionization for the determination of selected chlordane and nonachlor isomers (SI Figure 2). Liquid chromatography was used to isolate PCB congeners and the less polar pesticides (hexachlorobenzene, heptachlor, and 4,4′-DDE) from the more polar pesticides, such as the isomers of hexachlorocyclohexane, chlordane, nonachlor, and selected DDT compounds, prior to GC analyses. SI Figure 4 demonstrates the complexity of the house dust material in terms of the chlorinated species pattern in the PCB and lower polarity pesticide fraction as well as the absence of hexachlorobenzene (
